Devices and methods are used in the prior art, in particular for the detection of biomolecules such as nucleic acids or proteins. In the case of protein assays, the proteins couple e.g. to specific monoclonal antibodies, while DNA or RNA strands are detected by using respectively complementary nucleic acids as catcher molecules.
Most nucleic acid and protein detection methods by use of biosensors require a marking of the biomolecules to be examined. The molecular markers used for this purpose may be fluorescent, luminescent or electrically or magnetically active molecules or particles (quantum dots, magnetic beads). After a hybridization e.g. with complementary DNA catcher molecules in a homogeneous phase or at a microarray, the markers are detected at the bound biomolecules by means of optical, electrical or magnetic measuring methods.
One exception is the gravimetric method, which, with the aid of piezosensors, detects the change in mass through addition of molecules to the sensor surface. The nucleic acids or proteins do not need to be marked in this case. What prove to be disadvantageous, however, are the relatively low sensitivity, the small dynamic measurement range and the relatively complicated production methods for producing the piezooscillators under the sensor layers.
In the case of the known array-based detection methods, before the hybridization or binding of the analyte to the catcher molecules, markers are bound to the sample molecules (analyte) to be detected. The markers are detected after a hybridization or binding that has taken place. For this purpose, the microarray is introduced into an evaluation unit that detects the optical, electrical or magnetic marker signals. For this purpose, the evaluation unit contains a sensor array, which measures the signal emission of each individual array dot in parallel or sequentially. This gives rise to stringent requirements made of integration and homogeneity of the sensor array.